Typically, when Google shows a clickable headline in the search results, it pulls from your title tag meta data in the source code of the page. There are of course plenty of times where Google will rename the headline depending on the query.
What is new is that Google seems to be appending the brand followed by a colon before some titles or headlines in the search results. Here is an example:

Now if you look at the source code of this site you will see the title is not written this way:

Why is this happening, we are not sure. Google has not commented on this yet.
Gordon Campbell also noticed this and posted about it.
Forum discussion at Google+.

Comments:
Paul
02/28/2013 02:31 pm
Hello, yes i noticed this a couple of weeks ago when I searched for near and far removals. This appears with Near & Far Removals: Removals Nottingham
Vanessa Fox
02/28/2013 02:50 pm
What's the query in these cases? It looks like in the example in the screenshot, [york fitness] is part of the query so Google may be trying to better craft a title to match what the searcher is looking for.
Barry Schwartz
02/28/2013 02:51 pm
Yea, see the thread I linked to for more examples. The colon thing with that is interesting.
Josh
02/28/2013 03:35 pm
This has been happening for a while now. Google is picking brand names over stuffed keywords for title. Title tags for any given site will change depending on context; eg "company + product" vs "products", etc. They're simply catering to the end user for brand awareness. They started with picking description text and going to title is logical and something I can actually agree with... More or less.
Mikel Zaremba
02/28/2013 05:14 pm
Someone light up the Yoast signal before we lose title tags.
SEchecker
02/28/2013 05:48 pm
90% of our titles are allread 1 year index like: "Thats our title you are reading! - BRAND" and ofc BRAND is not in the title meta
Jonas Lindblom
02/28/2013 07:10 pm
Good to know that I don't have something wrong with my eyesight :-) I have seen this for our site www.patroner.se since Monday in Swedish serp for our main keyword "Bläckpatroner"
Jeff F
02/28/2013 09:06 pm
[Urgent Care Braintree MA] is a great example for Doctors Express. I noticed this started appearing last week.
John
03/01/2013 01:48 am
Yes! My website had happened!
Julien Brandt
03/01/2013 04:19 am
Yup noticed this a few days ago. Google changes up the headline in some cases but this is new. Interested to see what Google says about it...
anil kumar pandey
03/01/2013 06:23 am
Yes I am also observing colon thing in titles from last 2 weeks.
Guest
03/01/2013 06:55 am
Google recently made some changing in the page title to present with colons as a page separations. It some new treat hyphens from google for the keyword separators.
Saroj Nayak
03/01/2013 07:29 am
I have twit this few days before.. It's nice, but ranking of some keywords dropped!!!
Alex
03/01/2013 09:38 am
I've had that happen to my website - www.justgirls.co.nz - JustGirls is the brand, and in the title-tag that sits at the end. Google has placed this in the front followed by a colon. I think it's really good to do that, but yea noticed a drop in rankings. Google needs to fix its SERPs asap... alot of struggling webmasters (who strictly follow Webmaster Guidelines).
Felipe Bazon
03/01/2013 01:52 pm
I´ve seen that didn't paid much attention to it. Will keep an eye on the SERPs here in Brazil for that.
Jimmy Maddox
03/01/2013 04:35 pm
Yes I hate that. I have my phone number embedded in the title and I cant begin to tell you how many times customer will hot dial it on their mobile devices and I get sales. When Google renames the title my phone number is never included and I lose potential business.
Matt Lacroix
03/01/2013 05:32 pm
I noticed this last Thursday for a few sites I work on. At the time, I wasn't sure what was going on so I am glad to have come across this article. Does anyone have any more information on this? Links or updates from Google?
Stacey Mayer
03/02/2013 12:43 am
How is this supposed to help us as searchers or site owners? I'm not sure.
Murthy Seo
03/02/2013 05:45 am
This changes willl be for over stuffed in title and pick the brand name to reach their audience instead of keyword stuffing. but most of webmaster affecting while doing geniune optimizing and ranking. google should be conssidered this
Govind Singh
03/02/2013 10:31 am
but this is a miner case and he alredy put this in title tag as last keyword i don't this google plce any thing york fitnesh is brand name,
DarthVemin
03/20/2013 01:00 pm
I don't think this has anything to do with keyword stuffing in the title tag. I've been monitoring this for a while and the sites it has happened to were very different in terms of keyword density and title lengths. Who knows what Google is up to. Either somebody will work it out or Google will change something again and the titles will go back to how they were.
David Forster
03/30/2013 07:04 pm
Interesting stuff; Clearly Google is looking for uniqueness in it's snippets, not a bunch of first page results with identical keyword stuffed Meta titles and descriptions. I actually went on a mini-rant at a local marketing meetup - if you're so inclined: http://www.adster.ca/blog/are-keywords-in-meta-tags-still-important-a-sordid-past-and-promising-future
FuqG
04/05/2013 09:40 am
Is there any update on this matter? this is pretty annoying and has no positive effects